1999 Park Avenue EGR issues

[The_Buttler]

Hello, all! I have a 1999 Park Avenue base model 3.8 that is having some issues.

It all started with the terrible gas mileage and the check engine light for o2 sensors. I replaced them and things were getting better until the light came back on...this time for egr valve. The car would occasionally stall, but it would start back up after cooling down. So I replaced the egr valve, only to have the light come back on and still stall from time to time.

Here is the kicker...I have the same egr on my truck and I just tested both on it. Fully functional. But not functional on the buick.

Summary: getting a cel for egr even though valve is fully functional, stalls when warm, starts back up when cold.

Please help! My car stalled at a four way stop sign the other day so this hazard must stop! Any tips/hints/advice would be greatly appreciated!

 

[HotZ28]

You evidently have a heat related problem with the ICM, or the CKPS. Even though,the EGR code is set, it will not cause the stalling you mentioned. The EGR code could be from a restriction in the EGR tubes. Have you checked that?

 

[The_Buttler]

Would I be getting a cel with either icm or ckps? I can still check them, I was just wondering. Speaking of which, what is the best way to test them?

I checked the tubes when I replaced my intake manifold gaskets a few months ago. They were clear, but I can check again.

Thanks for the help!

 

[HotZ28]

Would I be getting a cel with either icm or ckps?

Not necessarily, it takes counts & time to set codes.

I can still check them, I was just wondering. Speaking of which, what is the best way to test them?

You should have the links for testing the ICM, EGR & CKPS attached. If not, we will try again. This site is getting rather funky with posting! If you still can not see the links, PM me and I will try to redirect it there.

http://easyautodiagnostics.com/gm_maf_testing/test_maf_gm_1.php
http://easyautodiagnostics.com/gm_ignition_3800/test_ignition_module_1.php
http://easyautodiagnostics.com/gm/3.8L/how-to-test-the-throttle-position-sensor-1

 

[GRMick]

Hello Buttler;

It may make sense check the catalytic converter function. If the converter has checked out, when hot, the engine management system may be trying to inject so much EGR that it's causing the stalling issue. When cold, the engine management system limits EGR until the engine is warmed up. The system may read this as a EGR failure.

Saw a similar issue with our 97 PA, although it just ran rough when hot, only stalled once, and no CEL. Replaced, both oxygen (O2) sensors and only saw a small improvement. Using an OBDII reader, I then monitored both oxygen sensor outputs. If the converter is working right, the front O2 sensor signal output should be bouncing up and down, while the rear O2 sensor signal output should stay almost constant. Both of the O2 sensor signal outputs will bounce if the converter is failed. I replaced the converter with a new one, and the rough running/stalling problem was resolved. It's been about 6 months now with no more problems.

The question for me then became why did the converter fail. Sometime they just go bad (catalyst at end of its useful life). However, it could also be from burning motor oil (piston rings, valve guides etc), from "burning" coolant due to intake/cylinder head gasket leaks, or if silicone sealant was used upstream of the catalyst and it fouled the converter. In my case, I believe it was a combination of age or burning coolant. If the root problem is not corrected, the new catalyst will just fail again.

Just my 2 cents. Hope this helps.